Now she seems like a totally cool character that will want to kick in the teeth of anyone who messes with her. But the hairdo of hers totally turns me off the character please tell me we can change it...

I would say you're just not that physically into her, which is probably part of the point. Not everyone is going to be attracted to every character, such as the instance of Jack's tattoos, Miranda's kind of puffy hair, etc. Some of the physical appearances are there to serve an underlying purpose (Jack's tattoos), while others are just things that have really nothing to do with the character. In this case, hair is normally a thing without a story to it (apart from Jack, having a story for everything in her body), so Cora's hair is likely just that and something you should not mind if interested in the actual person. Or if it's that much of a turn-off, just don't use her. Although, I'm sure they'll be implementing some system to track companion usage to have more realistic relationships, so that may not be ideal, but it all rides on how you want to play.